Wbs of Constructing Building

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Project Management
Dr. James A. Bednar
jbednar@inf.ed.ac.uk
http://homepages.inf.ed.ac.uk/jbednar

SAPM Spring 2006: Project Management

1

Project Management
A project is ‘a temporary endeavour to produce a unique
product, service, or result’ (PMI 2004). Project
management (PM) techniques were originally developed
for waterfall-type projects like building construction.
PM focuses on planning, scheduling, monitoring, and
controlling the complex interdependencies among subtasks.
PM techniques are particularly relevant when considering
the entire project in which software development is
embedded, which includes other activities such as
documentation, training, hardware, etc.
SAPM Spring 2006: Project Management

2

Example project
Consider building a garden
Roof

shed, which involves
designing the shed,

Framing

figuring out what materials
Siding

are needed, ordering or
purchasing the materials,
and putting together the
Foundation

various parts.

Some of these tasks depend on the others, some must be
scheduled, some take labor, etc.
SAPM Spring 2006: Project Management

3

Project management tasks
Need to figure out:

• What needs to be done
• What order they can be done
• How long each will take
• How long the whole project must take in principle
• How long the whole project is expected to take, given
finite resources

SAPM Spring 2006: Project Management

4

Work Breakdown Structure
A WBS is a diagram showing the major subtasks of the
project:
Build Shed

Planning

Obtaining Materials

Constructing
Pour foundation
Build frame
Install siding
Install roof
Finish (door, etc.)

Rule of thumb: break things down as far as necessary to
estimate and schedule them, and no further.
SAPM Spring 2006: Project Management

5

Network diagram
Build Shed

Materials list

Order materials

Deliver materials

1 day

1 day

1 day

7 days

Install siding

Pour foundation

Build frame

1 day

2 days

1 day

Install roof

Finish
1 day

2 days

Network diagrams can be constructed from the WBS,
adding dependencies and estimated durations. See slides
on estimation for caveats. (Dates are optional.)
SAPM Spring 2006: Project Management

6

Critical path
Build Shed

Materials list

Order materials

Deliver materials

1 day

1 day

1 day

7 days

Install siding

Pour foundation

Build frame

1 day

2 days

1 day

Install roof

Finish
1 day

2 days

The critical path is the longest path through the network
diagram – it is the minimum duration of the project if there are infinite resources (so that tasks can occur in parallel) and accurate estimates.
Here, everything but putting up the siding is on the critical path, and must happen in the order specified.
SAPM Spring 2006: Project Management

7

Slack
Build Shed

Materials list

Order materials

Deliver materials

1 day

1 day

1 day

7 days

Install siding

Pour foundation

Build frame

1 day

2 days

1 day

Install roof

Finish
1 day

2 days

Tasks not on the critical path have slack – the duration by which they can be late without making the project later
than the critical path duration.
Here, putting up the siding has one day of slack: one day
longer than estimated is ok, but if it takes longer it will be the new critical path, and delay the project.
SAPM Spring 2006: Project Management

8

PERT/CPM Charts
Network diagrams come in a variety of flavors with
different names:
A Program Evaluation and Review Technique (PERT)
chart shows dependencies and time estimates, using
3-point estimates.
The Critical Path Method (CPM) chart is a related
alternative, using single estimates.
Both show similar information, but use different methods
for calculating the critical path and slack.
SAPM Spring 2006: Project Management

9

Gantt Chart

A Gantt chart shows the tasks and their...
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